Update on the situation of thousand cankers disease in Italy
In 2013, both Geosmithia morbida and Pityophthorus juglandis (Coleoptera: Scolytidae - walnut twig beetle) the causal agents of thousand cankers disease (EPPO A2 List) were recorded for the first time in Europe in the Veneto Region (North-Eastern Italy) on black walnuts (Juglans nigra) (EPPO RS 2014/001). In 2014, both pests were also found on English walnut (Juglans regia). Since 2014, official measures have been put in place in the Veneto region to prevent the spread of the disease, including restrictions on the movements of plants for planting and wood products of Juglans and Pterocarya outside infested areas and surveys in nurseries producing Juglans and Pterocarya in the demarcated zones. Since 2013, the Phytosanitary Service of the Veneto Region has been performing a detailed field survey. In 2015, a survey was also carried out in 50 sites scattered within the regional territory outside the demarcated areas. Results of the 2015 survey indicated that there was no evidence that thousand cankers disease has spread in Veneto region beyond the boundaries of the currently demarcated areas, although P. juglandis was detected in 4 new sites. In Veneto region, it is estimated that the infested area covers approximately 70 000 ha. Surveys were also conducted in neighbouring regions. In Lombardia, P. juglandis was trapped in 2014 in the province of Mantova but G. morbida was not detected and no symptoms were observed. In Friuli-Venezia Giulia, 2 adults of P. juglandis were trapped in the province of Pordenone in 2015, but G. morbida was not detected and no symptoms were observed. In Piemonte, both P. juglandis and G. morbida were detected in 2015 in 2 sites close to the province of Torino and symptoms were observed. It is concluded that considering the large area where the pathogen and its vector are present, their eradication from Italy did not seem feasible. Containment measures can be applied and should be based on specific and intensive surveys of both the pathogen (sampling and isolation from P. juglandis, bark beetle holes, cankers, wood consignments) and the insect vector (pheromone traps). In addition, inspections at points of entry into the EU and regulations of the main commodities (i.e. round wood, firewood, bark, plants for planting) would help to prevent further introductions and spread.
The situation of both Geosmithia morbida and Pityophthorus juglandis in Italy can be described as follows: Present, Veneto (70 000 ha around the province of Vicenza) and in Piemonte (2 sites). The vector, P. juglandis, has been trapped in small numbers in Friuli-Venezia Giulia and Lombardia. Under official control.
Sources
Montecchio L, Vettorazzo M, Faccoli M (2016) Thousand cankers disease in Europe: an overview. Bulletin OEPP/EPPO Bulletin 46(2), 335–340.